Various types of extruded articles require surface coatings be applied to a plurality of selected surfaces without coating the entire surface of the extruded article. For instance, extruded elastomeric articles such as automotive window and door seals, fluid hoses, weather stripping and the like are extruded in specific cross-sectional designs which often require selective surface coating of separated surfaces. For example, automotive window seals require special slip- and abrasion-resistant surface coatings adjacent the window for engaging the glass so it can be raised or lowered easily without sticking to the window seal engaging surface. The remaining surfaces are generally maintained free of such coatings.
U.S. Reissue Pat. No. 30,789, relates to a process for coating an inflexible sheet substrate with a relatively thick coating of extruded molten thermoplastic polymer to coat the sheet substrate with a thermoplastic plastic layer to form boards used in construction. The sheet substrate advances in a spaced relationship with the die lip of the applied molten thermoplastic while the advancing sheet substrate forms the second die lip of the extrusion coating die. The sheet substrate ordinarily is wood, although other substrates, e.g., metal or polymeric, can be used. This coating process is not practiced in conjunction with an extruded substrate and utilizes a preformed substrate.
U.S. Pat. Nos. 3,841,807, and 3,836,297, relate to rotating coating application devices in an oscillating relationship with an advancing sheet substrate for depositing two separate coatings on the substrate surface to provide a heat-fused, marbleized plastisol coating on the substrate. This coating application process is not used in conjunction with an extruded substrate.
U.S. Pat. No. 3,155,540, relates to extrusion coating of fabrics by progressively feeding fabric and extruding coating material onto the fabric in a predetermined design and fusing the coating material to the fabric substrate. Similarly, U.S. Pat. No. 4,623,501, pertains to photographic photosensitive materials where photographic emulsions are applied to a belt-like substrate (web) by a coating means having auxiliary coating supply pipes interconnected to the coating application reservoir to prevent the coating from being stagnated within the coating supply cavity prior to applying the coating to the substrate.
U.S. Pat. No. 4,093,414, relates to a single die for co-extruding a high density polyethylene skin layer in a concentric relationship over a cellular polyethylene primary layer where the extruded layers provide cylindrical insulated layers for telephone wires. The two layers of insulating material are applied successively with a melt-flow separator disposed between the insulating layers prior to merging proximate the discharge tip of an extruder for the telephone wire. Similarly, U.S. Pat. No. 4,889,669, relates to a process for extruding two different resin compositions in the form of a laminate through a T-die to produce a foamed thermoplastic article. A similar coextrusion process for thermoplastic articles is disclosed in U.S. Pat. No. 4,856,975, wherein flat articles such as siding are extruded. The coextrusion process is based on a coextrusion block which enables the extruded capstock material to straddle the extruded substrate material.